Device for body care

ABSTRACT

An electromagnetic pump for supplying liquid pressure pulses to oral hygiene devices imposing different loads thereon includes a plunger-core driven in one direction by an electromagnetic circuit supplied with constant frequency pulses at power line frequency, a spring providing a restoring force so that the plunger-core reciprocates. The plunger-core drives a pump for producing the liquid pressure pulses, advantageously by using one end of the plunger-core as the piston of a pump. The mechanical resonant frequency of the plunger-core and spring is higher than the applied pulse frequency, and predetermined to yield an approximately constant amplitude of reciprocation for different loads imposed on the pump.

7 United States Patent Moret [4 1 Jan. 18,1972

Institut de Recherche et de Diffusion Industrielle P.G.E. Woog, Geneva, Switzerland 22 Filed: Dec. 15,1969

211 Appl.No.: 885,221

[72] Inventor:

[73] Assignee:

[30] Foreign Application Priority Date Dec. 13, 1968 Switzerland ..l8573/68 [52] US. Cl ..417/417,417/298 [51] Int. Cl. ..F04b 35/04, F04b 49/00 [58] FieldofSearch ..4l7/298,4l5,416,4l7

[56] References Cited UNITED STATES PATENTS 1,446,511 2/1923 Little ..417/298 2,481,147 9/1949 Parker et al. ..4l7/4l7 2,630,345 3/1953 Mesh 3,381,616 5/1968 Wertheimer et a]. ..417/4l7 Primary Examiner-Robert M. Walker Attarney-Pennie, Edmonds, Morton, Taylor and Adams [57] ABSTRACT An electromagnetic pump for supplying liquid pressure pulses to oral hygiene devices imposing different loads thereon includes a plunger-core driven in one direction by an electromagnetic circuit supplied with constant frequency pulses at power line frequency, a spring providing a restoring force so that the plunger-core reciprocates. The plunger-core drives a pump for producing the liquid pressure pulses, advantageously by using one end of the plunger-core as the piston of a pump. The mechanical resonant frequency of the plunger-core and spring is higher than the applied pulse frequency, and predetermined to yield an approximately constant amplitude of reciprocation for different loads imposed on the pump.

I4 A A I6 Pmsmamwmz 3.635593 19 FIG. I

FIG. 2

FIG. 3

INVENTUR MICHEL A. MOFET ATTOR NE Y DEVICE FOR BODY CARE BACKGROUND OF THE INVENTION The present invention relates to a pump for producing a stream of liquid pressure pulses, particularly for oral hygiene devices such as liquid jet devices and toothbrushes.

One of the constant problems in the field of oral hygiene is to make available to the public a simple and efficient system guaranteeing a perfect cleaning of the teeth and of interdental spaces as well as a stimulation of blood circulation in periodontal tissues.

Guinness British Pat. No. 382,430 describes a system composed essentially of a rotating electric motor which, through a transmission system including an eccentric, drives a piston supplied with different rather complicated accessories. With this apparatus, Guinness obtained a jet of pulsated liquid in the range of 3,000 pulsations per minute, for oral treatment. Mattingly U.S. Pat. No. 3,227,158 discloses a liquid jet device using lower pulse frequencies which has been commercialized. Other devices with intermittent pulsated jets have also been commercialized. However, up to now all such known devices have utilized rotating motors reciprocating a piston through a gearing and yoke mechanism, etc.

These devices, because of their complexity, present many disadvantages in use, such as mounting difficulties, high manufacturing costs, mechanical wear and tear of the gearing and of the yoke mechanism reciprocating the piston, noise, abnormal warming up of the motor and the risk of burning out, and high-power consumption. Moreover, an unsufficient watertightness can be fatal to the user if an accidental contact of the device with water occurs, and all the more if a liquid is added to the water which increases its conductivity, for example mouthwash salt. This electrical danger is further increased by the fact that the device is normally used in a bathroom or similar place and is intended for family use, including children, and can be easily dropped into the wash basin on which it usually stands.

The working frequency of the devices now on the market is generally in the range of 700 and 2,000 pulsations per minute, averaging about 1,200 per minute. These frequencies are unfavorable, especially if one wants to use an hydraulic motor driven toothbrush, as disclosed in U.S. Pat. No. 3,536,065. Since the brush works at a frequency corresponding to that of the jet pulsations, such frequencies are too low, the average frequency corresponding to 20 hertz. It has been medically proven that a frequency range between 50 and 70 hertz should be reached by the brush, in order to provide an optimal brushing and polishing.

The present invention provides a much simpler pump than the systems referred to above. Also, the pump operates without any mechanical transmission in synchronization with the power mains at 50 or 60 hertz, and thus makes it possible to optimize the washing and brushing functions. Further, the pressure pulse output can easily be modulated as disclosed in U.S. application Ser. No. 849,464 to yield, for example, pulses at a rate of 3,000 or 3,600 per minute which are modulated at a frequency between 200 and 300 per minute.

SUMMARY OF THE INVENTION In accordance with the invention, an electromagnetic pump is employed comprising a reciprocally mounted plunger-core including a plunger and a core of magnetic material united therewith. Elastic means such as a coil spring provides a restoring force for the plunger-core. The plunger-core is driven by an electromagnetic circuit including a coil which is energized by constant frequency current pulses. The current pulses are advantageously derived from a power mains alternating current source of 50 to 60 hertz, as by a simple rectifier circuit, and the plunger-core reciprocates at the corresponding frequency.

The plunger-core drives a pump including an inlet connection for supplying liquid to the pump and an outlet connection for supplying liquid pressure pulses from the pump to an oral hygiene device. In a specific embodiment one end of the plunger-core forms a piston which reciprocates in a cylinder, and valve means cooperates with the piston and cylinder to form the pump. The pressure pulses are supplied to an oral hygiene device such as a water jet of an hydraulically operated toothbrush.

Such devices impose substantially different loads on the pump which would normally decrease the amplitude of oscillation or reciprocation of the plunger-core as the load increases. For example, the load imposed by water jet operation may be considerably less than the load imposed by toothbrush operation. To prevent a substantial decrease in amplitude of reciprocation under higher load conditions, the plunger-core and elastic means are designed so that the no-load mechanical resonant frequency of the reciprocating :system is substantially higher than the frequency of the current pulses applied to the coil of the electromagnetic circuit, and predetermined to yield an approximately constant amplitude of reciprocation for the various loads encountered in normal use. In one particular embodiment a no-load resonant frequency about 10 hertz higher than the applied pulse frequency was found satisfactory.

The construction and simplicity of the pump of the invention permits convenient embedding in an insulating material of the energizing coil and all components carrying an electric current, thereby eliminating danger to the user in case water enters the casing or the pump is accidentally dropped into water.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a front view of a specific embodiment of the invention;

FIG. 2 is an axial cross section ofthe embodiment of FIG. 1; and

FIG. 3 represents schematically the mechanical resonance curves in idle running and under two different loads.

DESCRIPTION OF THE SPECIFIC EMBODIMENT FIGS. 1 and 2 represent an electromagnetic pump including a cylindrical electromagnet with an oscillating plunger-core l which works as a piston elastically mounted by means of a return spring 2, the spring being fixed on-the one hand on the flange 10 and on the other to the plunger-core 1. The electromagnet comprises a metallic core 3 and a coil 4 overmolded with a magnetic switch 5. The latter is constituted by a pair of magnetizable electric contacts enclosed in a bulb and controllable from outside by means of a permanent magnet 13 movable by a control knob (not shown). A diode 6, a silicon diode for example, is also molded into the thermoplastic or thermosetting insulating material, constituted for example of epoxy resin, which also protects the connections of the supply cord 20.

The core 3 conducts the magnetic flux of the coil 4}. This flux is closed by the plunger-core l. THe core 3 consists of a rear flange 8, which guides the plunger-core 1 through a bearing 9, a front flange l0 separated from the plunger-core 1 by an air gap, and an external framework 11 provided with cooling ribs. All these components of the metallic core, as well as the plunger-core l, are slotted in order to avoid excessive heating caused by Foucault currents.

On the flange 10 a pump 7 is mounted. It comprises a body 14, an inlet valve 15 and a pressure control shaft 116 limiting the motion of the inlet valve 15, thus preventing the valve from coming back on its seat and thereby regulating the pressure. The liquid to be pumped comes out of a reservoir (not shown), as indicated at A, and is supplied through coupling 19 to the interior of the pump. Pressure pulses pass out of the pump as indicated at S, through a coupling 17. The pump piston is an integral part of the plunger-core 1 and includes a ring 18 which provides a watertight seal with the pump cylinder.

Instead of the piston pump specifically shown, it would be possible to use other types of pumps, such as diaphragm pumps or the like, driven by the plunger-core.

A current pulse going through the coil 12 creates a magnetic field which tends to close, thereby driving the plungercore in one direction towards the pump and compressing the spring 2. At the end of a current pulse the magnetic flux ceases and the restoring force provided by spring 2 drives back the plunger-core 1 towards the rear part. The plunger-core overpasses its rest position due to its kinetic energy, thereby placing the spring in tension and drawing the core back toward its rest position. This assembly constitutes an oscillating mechanical system. The spring can be replaced by any other elastic element such as blades, use of rubber, etc.

The oscillating motion frequency given to the plunger-core is equal to that of the alternating current frequency, i.e., to the mains frequency of 50 to 60 hertz, because alternate half-cycles are suppressed by the diode 6, which is connected in series with the coil.

As far as usual mechanical oscillating systems are concerned, the vibrating element amplitude reduces as a function of the load. This phenomenon is undesirable in this case, since the output should remain as constant as much as possible, in-

dependent of the load, for example during oral washing when a spraying tip is applied against teeth or gums and when using a toothbrush appliance. In order to eliminate this incompatability, the oscillating system, which is composed of the plunger-core, the spring, and the portion of the pump driven by the plunger-core, is built in such a way that the change in resonance frequency of the system between idle running or no-load condition and the maximum load condition is in the range of about hertz. Thus, when there is no pump load, the system is tuned to a frequency of about 10 hertz abovethe network frequency to which is connected, and consequently the oscillation amplitude is less than would be produced if the system were tuned to the network frequency. As soon as the load increases, the resonance frequency of the oscillating system shifts and reduces progressively. This results in a practically constant amplitude of oscillation under different load conditions. In other words, the working point slides and goes up towards the top of the resonance curve, whereas the amplitude of the resonance lowers gradually because of the damping due to increasing load.

FIG. 3 represents those resonance curves. The abscissa is the frequency f and the ordinate is the oscillating amplitude 1. Curve 1 corresponds to the operation of the device under idle running or no-load condition; curve 2 to the utilization of the device under an intermediate load condition, for example, oral washing; and curve 3 to the utilization of the device under a higher load condition, for example for a toothbrush.- The quantity f represents the frequency of the network or power mains, and f represents the resonance frequency of the oscillating mechanical circuit under idle running or no-load condition, which is 10 hertz above the network frequency.

Since the energizing coil, as well as the reed switch and the diode, are overmolded in plastic insulating material, the device has an absolute watertightness. Also the device operates quietly and satisfactorily while at the same time being simple and compact.

It is moreover possible to modulate the pulsated jet as described in U.S. Pat. application Ser. No. 849,464, as well as to supply the output S through a flexible tube to an appliance head allowing either water jet or toothbrush operation, as described in U.S. Pat. No. 3,536,065. In the latter use, owing to the fact that the pump system is not rigid as in other known systems, there is less danger of bursting the tubings or the con nections by overpressure. Furthermore, if a jet-tip obturation should occur and reduce the oscillation amplitude of the piston toward zero, the current would reduce because of the modification of the motion impedance, instead of increasing as in the case of the usual rotating motor.

On the other hand the piston is an integral part of the oscillating plunger-core and there is only one movable part, thereby re ucmg friction and wear and tear to a strict minimum. Such a construction is moreover of great manufacturing and mounting simplicity, and its cost price is all the lower.

I claim:

1. An electromagnetic pump for supplying liquid pressure pulses to oral hygiene devices imposing different loads thereon which comprises a. a reciprocally mounted plunger-core including a plunger and a core of magnetic material united therewith,

b. an electromagnetic circuit including a coil for driving said plunger-core in one direction,

c. elastic means for producing a restoring force on said plunger-core opposite to said one direction,

d. means for supplying pulses of constant frequency to said coil to reciprocate said plunger-core at the frequency of said pulses,

. and a pump driven by said plunger-core,

. said pump including inlet and outlet connections for respectively supplying liquid to said pump and liquid pressure pulses from said pump to a said oral hygiene device,

g. said plunger-core and elastic means having a no-load mechanical resonant frequency substantially higher than the frequency of said pulses and predetermined to yield an approximately constant amplitude of reciprocation for different loads imposed on said pump by oral hygiene devices connected thereto.

2. An electromagnetic pump according to claim 1 in which one end of said pump forms a piston, and including a cylinder in which said piston reciprocates and valve means cooperating with said piston and cylinder to form said pump.

3. An electromagnetic pump according to claim 1 including means for deriving said current pulses from a 50 or 60 hertz power line frequency, said mechanical resonant frequency being about 10 hertz higher than said power line frequency.

4. An electromagnetic pump according to claim 1 in which the amplitude of reciprocation as a function of frequency of applied current pulses exhibits a resonant peak characteristic, said resonant peak decreasing in frequency and magnitude from said no-load resonant frequency to said constant frequency as the load imposed on said pump increases. 

1. An electromagnetic pump for supplying liquid pressure pulses to oral hygiene devices imposing different loads thereon which comprises a. a reciprocally mounted plunger-core including a plunger and a core of magnetic material united therewith, b. an electromagnetic circuit including a coil for driving said plunger-core in one direction, c. elastic means for producing a restoring force on said plunger-core opposite to said one direction, d. means for supplying pulses of constant frequency to said coil to reciprocate said plunger-core at the frequency of said pulses, e. and a pump driven by said plunger-core, f. said pump including inlet and outlet connections for respectively supplying liquid to said pump and liquid pressure pulses from said pump to a said oral hygiene device, g. said plunger-core and elastic means having a no-load mechanical resonant frequency substantially higher than the frequency of said pulses and predetermined to yield an approximately constant amplitude of reciprocation for different loads imposed on said pump by oral hygiene devices connected thereto.
 2. An electromagnetic pump according to claim 1 in which one end of said pump forms a piston, and including a cylinder in which said piston reciprocates and valve means cooperating with said piston and cylinder to form said pump.
 3. An electromagnetic pump according to claim 1 including means for deriving said current pulses from a 50 or 60 hertz power line frequency, said mechanical resonant frequency being about 10 hertz higher than said power line frequency.
 4. An electromagnetic pump according to claim 1 in which the amplitude of reciprocation as a function of frequency of applied current pulses exhibits a resonant peak characteristic, said resonant peak decreasing in frequency and magnitude from said no-load resonant frequency to said constant frequency as the load imposed on said pump increases. 